1. Field of the Invention
The present invention relates to a continuous flow intersection and more particularly to a two grade level street crossing intersection enabling continuous traffic flow. The present invention permits traffic to turn from a left lane and merge from a right lane with intersecting traffic.
2. Description of Related Art
Vehicular traffic on many city streets has increased to the point that a conventional single level interchange cannot effectively handle the volume. Multi-level street crossing interchanges which permit continuous traffic flow are common on interstate highways, but they are impractical for use in a crowded city environment. They usually include large radius cloverleaf turns covering a large land area, and typically also include traffic lanes stacked up on three or more grade levels. The cost of land acquisition to build such an interchange for a busy city street intersection would be prohibitive. For aesthetic purposes no more than two grade levels should be present. Preferably, one of the grade levels should be below ground level. A preferred interchange should also enable optional U-turns and a continuous flow of pedestrian traffic with minimal exposure to vehicular traffic.
An example of a typical large interstate intersection is illustrated in U.S. Pat. No. 3,107,509, issued to A. O. Cedeno et al on Oct. 22, 1963. This intersection requires use of extensive adjoining property to accommodate its wide turning lanes.
U.S. Pat. No. 2,946,267, issued to A. O. Cedeno et al on Jul. 26, 1960, is illustrative of a traffic intersection which can be used for city streets. However, no provision is made for U-turns, and making right turns is unnatural because they must be initiated from the left side of the streets. Further, more than two grade levels are required, and all through lanes must change in grade level at the street intersection.
U.S. Pat. No. 2,949,067, issued to A. O. Cedeno et al on Aug. 16, 1960, discloses a traffic intersection similar to that of U.S. Pat. No. 2,946,267, but providing for left turns from the left side of the streets. However, it lacks any provision for U-turn traffic. In addition, thru traffic in the intersection is reversed for the normal flow of traffic.